Coaxial cables are widely used in the cable television and telecommunications industry to distribute cable television and other electrical signals. Such cables include a central inner conductor surrounded by a low loss, high dielectric foam. The foam dielectric is, in turn, surrounded by a metallic outer conductor which may be cylindrical or corrugated. A protective insulating jacket, or sheath, surrounds the metallic outer conductor. The ends of such coaxial cables must be connected to junction boxes, amplifiers, and other coaxial ports, and coaxial connectors are well known for terminating the ends of coaxial cables.
In order to properly transmit an electrical signal, a coaxial connector should ensure that a reliable electrical connection is achieved between the outer body of the connector and the outer conductor of the coaxial cable. Likewise, a suitable coaxial connector must achieve a reliable electrical connection between the center conductor of the connector and the inner conductor of the coaxial cable. In addition, reliable coaxial connectors must form a secure mechanical connection to the end of the coaxial cable, since mechanical separation of the connector from the end of the cable will interfere with successful transmission of the desired electrical signal.
Coaxial connectors are known which achieve secure electrical and mechanical coupling with the end of a coaxial cable. However, the complexity of such connectors, their relatively high parts count, and the burden imposed upon the technician during installation, are all significant for such known coaxial connectors.
Current coaxial cable connectors on the market consist of a number of moving parts, typically a standard front end which includes an inner terminal or center conductor, an outer terminal or outer body, a dielectric insulator for supporting the center conductor within the outer body, and a moveable back nut which encapsulates a number of seals, retaining rings and the like. U.S. Pat. No. 6,133,532 shows one such connector having a back nut which encapsulates three different moving parts (a locking device, guide surface and inner sleeve) as well as three separate O-ring seals. The large number of moving parts in the back nut portion complicates the fitting of a coaxial cable which usually requires the use of several specialized tools. Additionally, the risk of connector malfunctioning and mounting problems increases with a higher number of moving parts, since there is a greater chance that at least one part may be defective, missing or incorrectly attached.
Likewise, U.S. Pat. No. 4,952,174 to Sucht, et al. discloses a coaxial connector wherein the back nut houses a cone, a mandrel, a mandrel shell, a tined ferrule, and a seal ring. The cone operates together with the center conductor of the connector to bite into the inner conductor of the coaxial cable. The tined ferrule bites into the outer surface of the outer conductor of the coaxial cable and forces such outer conductor against the mandrel. Apart from the relatively large number of parts, there is no direct contact between the outer conductor of the coaxial cable and the outer body of the connector.
Similarly, U.S. Pat. No. 4,676,577 to Szegda discloses a coaxial connector for use with coaxial cable and including a front body, a center conductor supported within the front body and insulated therefrom, and a rear nut (or cap body). The center conductor of the front body includes a collet for receiving the inner conductor of the coaxial cable. An insulative seizure bushing is positioned within the front body to constrict the collet when the seizure bushing is axially displaced. The front body also includes a mandrel for being inserted into the coaxial cable just inside the outer conductor thereof; this mandrel is axially movable relative to the front body and engages the seizure bushing. The rear nut includes an outer conductor clamp member for gripping the outer surface of the coaxial cable outer conductor, as well as a clamp ring having a ramped surface and engaging an o-ring. As the rear nut is tightened onto the front body, the outer conductor clamp member engages a ramp on the front body causing the outer conductor clamp member to be radially compressed inwardly against the outer conductor of the coaxial cable; likewise, the outer conductor clamp member engages the ramped surface of the clamp ring, again forcing the outer conductor clamp member to be compressed against the outer conductor of the coaxial cable, while compressing the o-ring within the rear nut. Simultaneously, the outer conductor clamp member engages, and axially displaces, the mandrel and seizure bushing within the front body to constrict the center conductor collet.
U.S. Pat. No. 6,183,298 to Henningsen also discloses a coaxial connector having a main body, a bushing or back nut, a center conductor, and an insulator supporting the center conductor within the main body. The Henningsen '298 patent includes an axially displaceable member for radially compressing the center conductor of the connector about the inner conductor of the cable. However, the back nut, or bushing, again contains additional movable parts, including a slotted ferrule, an inner bushing, and a friction reducing disk.
Due to the large number of moving parts encapsulated in the back nut of most conventional connectors, the outer conductor must be thoroughly cleared of all glue and adhesive material that may hinder or jam the parts during mounting and tightening, or a poor electrical connection may result. This process can prove to be quite difficult and time-consuming.
The manufacture and assembly of conventional connectors is also expensive in terms of time taken and material costs due to the number of parts enclosed in the back nut, which have to be manufactured and assembled.
The present applicant filed U.S. patent application Ser. No. 10/869,105 on Jun. 15, 2004, entitled “Coaxial Connector with Center Conductor Seizure”, and the disclosure of such prior-filed application is hereby incorporated as if fully set forth herein. In this prior patent application, applicant disclosed a simplified coaxial connector for use with coaxial cable, including both rigid cable and semi-rigid corrugated cable, wherein the connector is comprised of a relatively small number of components. The connector disclosed in such prior application serves to both clamp a flared end of the outer conductor between the back nut and the connector body, and to seize the inner conductor of the coaxial cable. However, applicant has discovered that tightening of the back nut onto the connector body can sometimes apply a twisting force to the end of the coaxial cable. It is generally preferred to avoid twisting or rotation of the coaxial cable when the back nut is being tightened onto the body of the connector.
Accordingly, an object of the present invention is to provide an improved coaxial connector of the general type disclosed in applicant's prior-filed application identified above which minimizes any tendency for the end of the coaxial cable to be twisted as the back nut is tightened onto the connector body.
A further object of the invention is to provide such an improved coaxial connector that minimizes the number of components incorporated within such coaxial connector, thus reducing manufacturing expense, assembly time, and simplifying installation.
These and other objects of the present invention will become more apparent to those skilled in the art as the description of the present invention proceeds.